US5604973A - Process for the production of a vertical magnetic head - Google Patents

Process for the production of a vertical magnetic head Download PDF

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Publication number
US5604973A
US5604973A US08/393,359 US39335995A US5604973A US 5604973 A US5604973 A US 5604973A US 39335995 A US39335995 A US 39335995A US 5604973 A US5604973 A US 5604973A
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US
United States
Prior art keywords
substrate
mask
recesses
layer
recess
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US08/393,359
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English (en)
Inventor
Pierre Gaud
Henri Sibuet
Brigitte Desloges
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Assigned to COMMISSARIAT A L'ENERGIE ATOMIQUE reassignment COMMISSARIAT A L'ENERGIE ATOMIQUE ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DESLOGES, BRIGITTE, GAUD, PIERRE, SIBUET, HENRI
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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/10—Structure or manufacture of housings or shields for heads
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/1871—Shaping or contouring of the transducing or guiding surface
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/23—Gap features
    • G11B5/232—Manufacture of gap
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
    • G11B5/23—Gap features
    • G11B5/235—Selection of material for gap filler
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3176—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps
    • G11B5/3179—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps the films being mainly disposed in parallel planes
    • G11B5/3183—Structure of heads comprising at least in the transducing gap regions two magnetic thin films disposed respectively at both sides of the gaps the films being mainly disposed in parallel planes intersecting the gap plane, e.g. "horizontal head structure"
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49036—Fabricating head structure or component thereof including measuring or testing
    • Y10T29/49043—Depositing magnetic layer or coating
    • Y10T29/49046—Depositing magnetic layer or coating with etching or machining of magnetic material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/4902—Electromagnet, transformer or inductor
    • Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
    • Y10T29/49032—Fabricating head structure or component thereof
    • Y10T29/49048—Machining magnetic material [e.g., grinding, etching, polishing]
    • Y10T29/49052—Machining magnetic material [e.g., grinding, etching, polishing] by etching

Definitions

  • the present invention relates to a process for producing a vertical magnetic head and to a head obtained by the process.
  • a magnetic recording support for video equipment, data backups or computer memories comprises several tracks on which are entered informations in the form of magnetic domains.
  • metal-in-gap heads In order to meet these objectives, at present there are mainly two types of heads on the market, so-called metal-in-gap heads and sandwich heads.
  • FIG. 1 illustrates an example of a head of the second type.
  • the head shown has a substrate 2 supporting a magnetic circuit 4 constituted by a magnetic layer deposited on the upper face of the substrate, the circuit having at the front two pole pieces 5, 7 separated by a head gap 6 formed by an amagnetic spacer. Above the magnetic circuit the head also has an amagnetic superstrate 2'.
  • the head also has an opening 8 made through the magnetic layer, the substrate and the superstrate, as well as a conductor winding 9 passing through the opening 8.
  • the head shown in FIG. 1 is intended to cooperate with a recording support 20 oriented perpendicular to the substrate (or, what amounts to the same thing, parallel to its edge).
  • This type of head can be called “vertical” in the sense that the active surface is perpendicular to the surface of the initial substrate.
  • the width of the head gap is counted perpendicular to the substrate (or, what amounts to the same thing, parallel to the recording support). Its length, designated L, is counted in the direction of the relative displacement of the head and the support.
  • the height of the head gap, designated h is counted parallel to the face of the substrate supporting the magnetic circuit. In the case of head wear, it is the height h which is reduced.
  • a horizontal head is e.g. described in FR-A-2 604 021.
  • FIGS. 2a to 2d diagrammatically illustrate this known process.
  • a substrate 16 and, by different etching operations, some of which are anisotropic, as well as a thermal oxidation process, a vertical wall 24 on the substrate is obtained (FIG. 2a).
  • the wall 24 is made from silicon oxide or in other words silica.
  • a magnetic layer 26 is then deposited on either side of the wall and is then planarized (FIG. 2b).
  • the wall 24 then serves as an amagnetic spacer.
  • the magnetic circuit 28 is then defined in its overall form by photolithography (FIG. 2c).
  • the assembly is covered by a not shown superstrate and is given an opening 34 (FIG. 2d).
  • the spacer 24 obtained is made from a thermal oxide.
  • this causes stability or straightness problems in the case where the ratio between the width l and the length L of the spacer is large (in practice exceeding 20). This effect is due to a release of the stresses present in the spacer during the second etching of the silicon, the foot of the spacer being fixed, whereas its top is free. The reason is the difference in the nature between silicon and its thermal oxide (in particular expansion coefficient difference).
  • WO 92/02015 proposes other implementation forms, in which deposition firstly takes place of a magnetic material on one side of the vertical oxide wall, before carrying out the second silicon etching.
  • the corresponding process is complex and increases the number of lithography -etching-planarization sequences, so that it is scarcely suitable.
  • the present invention aims at obviating these disadvantages.
  • a spacer is produced, which is no longer of thermal oxide, but which is made from the same material as that forming the substrate, e.g. silicon if the substrate is made from this material. Moreover, the operations are simple and the magnetic circuit is produced in a single stage.
  • the present invention relates to a process for the production of magnetic heads of the type defined hereinbefore and which includes the following operations:
  • an etching of the substrate is performed through a first mask in order to form a pre-recess of limited depth
  • a thin material layer able to constitute a mask for a subsequent etching of the substrate
  • the thin layer is eliminated over at least part of the bottom of the pre-recess, whilst allowing it to remain at least along one of the vertical walls of the pre-recess,
  • a second mask is defined with an opening, which leaves free the pre-recess and the substrate on the side of the vertical wall covered by the thin layer,
  • the assembly is etched through the second mask, the thin layer remaining against the wall serving as a mask and preserving below it a vertical wall formed from the material constituting the substrate, the etching leading to the appearance of a first recess and a second recess separated by the vertical wall of the material constituting the substrate,
  • the first and second recesses are filled with a magnetic material
  • the assembly is planarized parallel to the substrate at least up to the vertical wall, which leaves two pole pieces separated by the vertical wall, which thus constitutes the amagnetic spacer of the head,
  • the assembly is machined in order to define a friction surface perpendicular to the surface of the substrate, the amagnetic spacer being level with the friction surface.
  • This process can use any conductor winding type and in particular a conductor winding wound through an opening (as in the case of FIG. 1).
  • the present invention also relates to a head obtained by the process defined hereinbefore.
  • this head is its head gap is formed by an amagnetic spacer made from the material forming the substrate.
  • an amagnetic spacer made from the material forming the substrate.
  • the gap is constituted by a vertical silicon wall.
  • FIG. 1 Already described, shows a prior art vertical magnetic head.
  • FIGS. 2a, 2b, 2c & 2d Show four stages of a known process for producing a vertical magnetic head.
  • FIGS. 3a to 3q Show various stages in a production process according to the invention.
  • FIGS. 4a to 4c Show a variant of the magnetic deposit.
  • FIGS. 5a and 5b Show the use of a substrate with a
  • the substrate used is of silicon and more specifically monocrystalline silicon of crystal orientation ⁇ 110>.
  • the starting product is a substrate 50 in FIG. 3a and deposition takes place of a first etching mask 52, e.g. of silicon nitride.
  • This first mask can be obtained by low pressure vapour chemical deposition and it can have a thickness of about 40 nm.
  • an opening 56 is made in the first silicon nitride mask (FIG. 3b).
  • the etching can be a reactive ionic etching.
  • the resin mask 54 is then removed, e.g. chemically with a nitric acid solution.
  • a pre-recess 58 with a depth of a few tenths of a micron.
  • use is e.g. made of a KOH solution with a concentration of 40% and at 70° C.
  • the depth of the pre-recess is a function of the sought geometry. It is a question of obtaining a compromise between a limited depth, which will minimize the asymmetry of the pole pieces obtained on each side of the spacer and a deeper etching, which will facilitate the subsequent obtaining of the mask necessary for the etching of the silicon for defining the spacer. For example, for a final recess depth of 5 ⁇ m, a depth of 0.3 ⁇ m can be adopted for the pre-recess 58.
  • a layer 60 of a material able to serve as a mask for a subsequent silicon etching operation (FIG. 3d). It is e.g. possible to carry out a thermal oxidation of the silicon and in this case the layer 60 is of silicon oxide (silica).
  • the thickness of the layer 60 is directly linked with the length of the desired head gap (counted in the movement direction of the recording support, i.e. horizontally in FIG. 3d). For example, a thermal oxidation of 0.3 ⁇ m can be carried out for a desired gap length of 0.2 ⁇ m.
  • FIGS. 3a to 3d are sections along a plane parallel to the plane of the future recording support, or in other words sections perpendicular to the upper face of the silicon substrate.
  • FIG. 3e is a plan view of the assembly. It is possible to see the silicon nitride mask 52 and its opening in which the pre-recess has been etched, together with the silicon oxide layer 60 covering the prerecess.
  • the dimension h represents what has been called in connection with FIG. 1 the "height" of the future head gap, but this dimension is not critical. It also evolves by decreasing as the wear of the head progresses.
  • the anisotropic etching of the initial mask 52 and the material 60 is followed by the anisotropic etching of the initial mask 52 and the material 60.
  • deposition takes place of a resin mask 66 and an opening is defined which frees the pre-recess and the upper face of the substrate on one of the sides of the pre-recess (FIG. 3f).
  • the silicon nitride 52 is removed together with the material 60, which is only left behind on the side walls of the pre-recess (particularly the right-hand wall 63) in the form of layers 62 and 64.
  • the mask 66 can be removed at this stage of the process by any known means.
  • FIG. 3g shows the assembly obtained at this stage in plan view.
  • the layer 62 remaining along the wall 63 will form a mask for etching the silicon.
  • This etching is an anisotropic etching process, e.g. using a KOH solution in a concentration of 40% at 70° C.
  • the depth of the etching corresponds to the desired head gap width (counted perpendicular to the substrate, i.e. parallel to the recording support). This width must correspond to the width of the track to be read.
  • FIG. 3h shows a first and a second recesses, respectively 70 and 72, separated by a vertical wall 68, which has been saved during the etching as a result of the mask 62.
  • This vertical wall 68 is necessarily made from the material forming the substrate, as a result of its formation method. It is therefore of silicon if the substrate is made from this material.
  • Deposition then takes place, preferably by cathodic sputtering, of an electrically conductive, locking under-layer 74, e.g. of iron-nickel (FIG. 3k) and in a thickness of approximately 0.1 ⁇ m.
  • an electrically conductive, locking under-layer 74 e.g. of iron-nickel (FIG. 3k) and in a thickness of approximately 0.1 ⁇ m.
  • the third resin mask 76 is then deposited (FIG. 3l) in which is formed an opening 77, which frees the two recesses 70, 72 and part of the substrate around the recesses.
  • electrolytic growth takes place of a magnetic material 78 using the layer 74 as the electrode.
  • the thickness obtained must exceed the depth of the recesses, so that the magnetic material 78 surmounts the vertical wall 68. For example, if the recesses have a depth of 5 ⁇ m, 6 ⁇ m of magnetic material 78 will be deposited.
  • FIG. 3o shows the assembly in section and FIG. 3p in plan view. It is possible to see the magnetic material separated into two pole pieces 80, 82 separated by the silicon wall 68 serving as an amagnetic spacer (the locking layer 78 deposited on either side of the silicon wall 68 not forming part of the amagnetic spacer, because as the layer is of iron-nickel it is magnetic).
  • the width of these two pole pieces, considered parallel to the spacer is not exactly the same as a result of the etching of the pre-recess 58 illustrated in FIG. 3c. However, the difference is small.
  • the width l in FIG. 3o corresponds to the part where the two pole pieces 80, 82 face one another. This width is the head gap width, considered parallel to the recording support.
  • This assembly is then covered by a not shown superstrate.
  • the head is then finished by the conventional operations of producing a conductor coil, e.g. by making an opening and the winding of a conductor wire.
  • the head is then completed by a machining for defining the friction surface 65 (FIG. 3q) and optionally for defining a non-zero angle between the head gap width and the direction perpendicular to the movement of the support.
  • the formation of the magnetic part 78 is not necessarily obtained by electrolytic growth by the bias of a conductive underlayer, as illustrated in FIGS. 3k to 3l. It would also be possible to operate by vapour phase deposition, e.g. sputtering, and this is illustrated in FIGS. 4a to 4c.
  • FIG. 4a it is assumed that the starting product was the subassembly of FIG. 3i.
  • a magnetic material 79 is deposited on the entire surface (FIG. 4a). This is followed by the deposition of a mask 81 covering the recesses 70, 72 and the periphery of the recesses (FIG. 4b). The magnetic material 79 is then etched through the mask 81 and the latter is eliminated.
  • the subassembly of FIG. 4c is obtained, which corresponds to that of FIG. 3m, less the conductive layer 74.
  • a variant of the process according to the invention consists of using a substrate 50 with a buried barrier layer 51 (cf. FIG. 5a).
  • the etching of the latter stops at the layer despite the presence of the pre-recess (cf. FIG. 5b which is the equivalent of FIG. 3i). The remainder of the process remains unchanged.
  • This substrate with the buried layer can be obtained either by oxygen implantation in a substrate followed by annealing in such a way as to obtain a buried oxide layer according to the known silicon-on-insulator (SOI) method, or by boron implantation.
  • SOI silicon-on-insulator
  • the material constituting the substrate then undergoes epitaxy.
  • a monocrystalline material is used for the substrate.
  • the process according to the invention illustrates the production of the pole pieces of the magnetic circuit.
  • the complete magnetic circuit can be produced at the same time as these pieces or in several deposition stages, the deposits occurring before the covering of the circuit by the superstrate.
  • the production process according to the invention lends itself well to a collective production procedure for heads like that described e.g. in WO 92/02015.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Magnetic Heads (AREA)
US08/393,359 1994-03-01 1995-02-23 Process for the production of a vertical magnetic head Expired - Fee Related US5604973A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9402330A FR2716995B1 (fr) 1994-03-01 1994-03-01 Procédé de réalisation d'une tête magnétique verticale et tête obtenue par ce procédé.
FR9402330 1994-03-01

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US5604973A true US5604973A (en) 1997-02-25

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EP (1) EP0670569A1 (ja)
JP (1) JPH07287813A (ja)
FR (1) FR2716995B1 (ja)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5883765A (en) * 1994-03-07 1999-03-16 Commissariat A L'energie Atomique Vertical magnetic head having first and second magnetic materials in specific shapes
EP0883109A3 (en) * 1997-06-02 2000-06-28 Deutsche Thomson-Brandt Gmbh Head drum with thin film heads
US6163435A (en) * 1996-02-15 2000-12-19 Commissariat A L'energie Atomique Vertical magnetic head having a magnetic circuit with a non-embedded part and having an integrated coil surrounding the non-embedded part
US6253445B1 (en) * 1998-02-24 2001-07-03 Samsung Electronics Co., Ltd. Planar thin film head and method for forming a gap of a planar thin film magnetic head
US6256864B1 (en) * 1998-02-11 2001-07-10 Commissariat A L'energie Atomique Process for producing an assembly having several magnetic heads and multiple head assembly obtained by this process
US6501619B1 (en) 2000-04-27 2002-12-31 Shipley Company, L.L.C. Inductive magnetic recording head having inclined magnetic read/write pole and method of making same
US6555294B1 (en) * 1998-07-28 2003-04-29 Commissariat A L'energie Atomique Method for collective production of magnetic heads with rounded bearing surface
US6718622B1 (en) * 1998-12-03 2004-04-13 Koninklijke Philips Electronics N.V. Method of forming an assembly of stacked layers
US20040156142A1 (en) * 2001-03-19 2004-08-12 Hitachi, Ltd. Magnetic head for perpendicular recording and magnetic disk storage apparatus mounting the head

Citations (1)

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Publication number Priority date Publication date Assignee Title
EP0418127A1 (fr) * 1989-09-12 1991-03-20 Compagnie Europeenne De Composants Electroniques Lcc Procédé de réalisation des pièces polaires et de l'entrefer de têtes magnÀ©tiques en couches minces pour application informatique audio ou vidéo

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JPH04153907A (ja) * 1990-10-15 1992-05-27 Mitsubishi Electric Corp 薄膜磁気ヘッドの製造方法
JPH0554326A (ja) * 1991-08-23 1993-03-05 Mitsubishi Electric Corp パターン形成法およびそれを用いた平面型薄膜磁気ヘツドの製法

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EP0418127A1 (fr) * 1989-09-12 1991-03-20 Compagnie Europeenne De Composants Electroniques Lcc Procédé de réalisation des pièces polaires et de l'entrefer de têtes magnÀ©tiques en couches minces pour application informatique audio ou vidéo
US5062196A (en) * 1989-09-12 1991-11-05 Compagnie Europeenne De Composants Electroniques Lcc Method of manufacturing the pole pieces and the gap of magnetic heads in thin layers

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Title
Patent Abstracts of Japan, vol. 16, No. 442 (P 1421), Sep. 16, 1992, JP 4 153907, May 27, 1992. *
Patent Abstracts of Japan, vol. 16, No. 442 (P-1421), Sep. 16, 1992, JP-4-153907, May 27, 1992.
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Patent Abstracts of Japan, vol. 17, No. 366 (P-1571), Jul. 9, 1993, JP-5-054326, Mar. 5, 1993.

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5883765A (en) * 1994-03-07 1999-03-16 Commissariat A L'energie Atomique Vertical magnetic head having first and second magnetic materials in specific shapes
US6167611B1 (en) * 1994-03-07 2001-01-02 Commissariat A L'energie Atomique Process for producing a vertical magnetic head
US6163435A (en) * 1996-02-15 2000-12-19 Commissariat A L'energie Atomique Vertical magnetic head having a magnetic circuit with a non-embedded part and having an integrated coil surrounding the non-embedded part
US6335846B1 (en) 1996-02-15 2002-01-01 Commissariat A L'energie Atomique Vertical magnetic head having a magnetic circuit with a non-embedded part and having an integrated coil surrounding the non-embedded part
EP0883109A3 (en) * 1997-06-02 2000-06-28 Deutsche Thomson-Brandt Gmbh Head drum with thin film heads
US6256864B1 (en) * 1998-02-11 2001-07-10 Commissariat A L'energie Atomique Process for producing an assembly having several magnetic heads and multiple head assembly obtained by this process
US6253445B1 (en) * 1998-02-24 2001-07-03 Samsung Electronics Co., Ltd. Planar thin film head and method for forming a gap of a planar thin film magnetic head
US6555294B1 (en) * 1998-07-28 2003-04-29 Commissariat A L'energie Atomique Method for collective production of magnetic heads with rounded bearing surface
US6718622B1 (en) * 1998-12-03 2004-04-13 Koninklijke Philips Electronics N.V. Method of forming an assembly of stacked layers
US6501619B1 (en) 2000-04-27 2002-12-31 Shipley Company, L.L.C. Inductive magnetic recording head having inclined magnetic read/write pole and method of making same
US20040156142A1 (en) * 2001-03-19 2004-08-12 Hitachi, Ltd. Magnetic head for perpendicular recording and magnetic disk storage apparatus mounting the head
US7475470B2 (en) * 2001-03-19 2009-01-13 Hitachi Global Storage Technologies, Ltd. Method for manufacturing a magnetic head for perpendicular recording

Also Published As

Publication number Publication date
JPH07287813A (ja) 1995-10-31
FR2716995A1 (fr) 1995-09-08
FR2716995B1 (fr) 1996-04-05
EP0670569A1 (fr) 1995-09-06

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